Field of the Invention
The present invention relates to a circuit configuration for driving an ignition coil, which is for example used for generating ignition sparks in spark-ignition engines.
Circuit configurations of this type have a semiconductor switch having a load path connected in series with a primary winding of the ignition coil, and having a control electrode for driving the semiconductor switch in accordance with a drive signal. In this case, the series circuit formed by the semiconductor switch and the primary winding is connected to terminals for a voltage supply.
If, in circuit configurations of this type, the semiconductor switch is closed in dependence of the drive signal, a current which rises over time flows through the primary winding. When the semiconductor switch is subsequently opened, the energy stored in the primary winding is transferred to a secondary winding of the ignition coil, in order to generate an ignition spark at a spark plug connected thereto.
The instant at which the ignition spark is generated or the semiconductor switch is opened is prescribed for the circuit configuration externally, depending on the engine data. Consequently, the period of time between the closing and opening of the first semiconductor switch may vary.
After the closing of the semiconductor switch, and thus the beginning of energy storage in the primary winding, circumstances can occur which should be avoided, such as, for example, an excessive heating of the circuit configuration.